DAMAGE TOLERANCE CERTIFICATION OF A FIGHTER HORIZONTAL STABILIZER

A review of tile program for the damage tolerance certification test o f a composite horizontal stabilizer (HS) of a fighter is presented. Th e object of this program is to certify that the fatigue life and damag e tolerance strength of a damaged composite horizontal stabilizer meet s the design requirements. According to the specification for damage t olerance certification, a test article should be subjected to two desi gn lifetimes of flight-by-flight load spectra simulating the in-servic e fatigue loading condition for the aircraft. However, considering the effect of environmental change on the composite structure, one additi onal lifetime test was performed. In addition, to evaluate the possibi lities for extending the service life of the structure, one more lifet ime test was carried out with the spectrum increased by a factor of 1. 4. To assess the feasibility and reliability of repair technology on a composite structure, two damaged areas were repaired after two lifeti mes of damage tolerance test. On completion of four lifetimes of the d amage tolerance test, the static residual strength was measured to che ck whether structural strength after repair met the requirements. Stif fness and static strength of the composite HS with and without damage were evaluated and compared.